From pharmaceuticals to coatings and adhesives, manufacturers are using self-cleaning filters to minimize waste and maximize profits
From filtering to concentrate or remove solids, remove impurities or extract valuable product, or to facilitate waste-stream cleanup and byproduct recovery, the fine chemical and pharmaceutical industry is cleaning up its act with self-cleaning filters and profiting to boot. In accordance with the recommendations of the EPA's Priority Hierarchy of Waste Management, a growing number of manufacturers with fine chemical-based products are shifting their focus from end-of-pipe pollution controls to minimizing waste at the source.
The reasons for this shift are well documented. Minimizing waste at the source provides a cleaner, safer environment; saves resources and money - in some cases, millions of dollars; and reduces long-term risk and liability. Also, by filtering early in the manufacturing process, the cost of filtration decreases significantly since capturing and eliminating undesirable solids is often much more difficult later in the process.
In both consumable chemicals such as pharmaceuticals and industrial chemicals used to formulate products such as coatings and adhesives, liquid and particulate are main ingredients. For manufacturers in these fine chemical industries, purity and clarity depend in large part on proper filtration, which has long been recognized for its ability to improve product quality, increase throughput, and protect downstream equipment in the production of a vast array of chemical-based products. Due to the predominant use of disposable media filters, however, it was also seen as a necessary contributor to a company's environmental impact.
Today, that view is changing as manufacturers with fine chemical-based products are tasked with the strategic corporate mandate to reduce the amount of waste they produce and dispose. As a result, these manufacturers are re-evaluating their filtration strategy and turning instead to self-cleaning filters, which promise not only to minimize waste at the source but also maximize productivity and increase profits.
The Hidden, Ongoing Costs of Disposable Media Filters
Traditionally, chemical engineers have opted for disposable media filters such as bags or cartridges due to their lower initial cost. While initial cost may be lower for small batch operations, this is seldom true for continuous operations that require a costly, redundant filtration system - including piping, valves, support, and service connections - to maintain production. Moreover, there are significant hidden costs associated with disposable media filters.
When users purchase disposable media filters, they often fail to account for the true costs of doing so. To begin, there's the ongoing disposable filter purchase price, which typically runs at least $3 per bag or cartridge per day, plus the ongoing cost of waste disposal. For non-hazardous waste, disposal is already $400-$800 USD per drum, while that of hazardous waste is approaching $1,000 per drum. It's not unusual for the typical pharmaceutical company or other fine-chemical based manufacturer to produce up to 20 drums per year of filter media for disposal, not counting the cost of treating or eliminating any run-off process fluids.
Beyond this, there are significant labor costs involved with transporting, handling and storing disposable filter media, as well as with replacing it. For example, for just a small 30-gpm cartridge filter with six 10-inch cartridges, the operator must remove 16 separate parts including the cover, compression seals, cartridges, and seal plates. The operator must reassemble all 16 parts with proper alignment to ensure good seals. Then someone must haul away the spent filter media.
There's also a housekeeping cost for cleaning any spillage from disposable media, along with increased emissions, safety risk, and liability. Then there's the potential cost of disposable media rupturing or overflowing (as bags sometimes do), contaminating product or machinery downstream and slowing production.
Finally, add the cost of buying, maintaining, and cleaning workers' protective clothing for replacing disposable media, as well as the extra time and labor required to fill out MSDS forms and other paperwork required for items hauled to landfills or incinerators.
Self-Cleaning Filters: A Bottom-Line Boosting Alternative
With the hidden, ongoing costs of disposable filter media as significant as they are, the trend in the fine chemical and pharmaceutical industry is now toward self-cleaning filtration with minimal need for labor. Variations of this, such as disc-cleaned filters (DCF), are helping producers of fine chemical products improve profit and worker safety while reaching waste minimization goals, as operations become more efficient.
Though an up-front capital expense, manufacturers of fine chemical-based products and their engineers are now realizing the extent that self-cleaning filters add to the bottom line. To start, a self-cleaning filter system automatically cleans itself while in use, allowing a single piping arrangement, minimal valving, and fewer connections, instead of complex, redundant systems. This translates into lower total system cost and reduced waste. A number of other benefits accrue as well including:
Automated cleaning minimizes disposal waste and labor costs
With cleanable filter media, there are no bags or cartridges to landfill or incinerate. Self-cleaning filter systems clean themselves within seconds of starting a cleaning cycle. They can be automated to clean themselves according to schedule, or only when necessary.
"Contrary to disposable media which tend to be replaced according to an arbitrary schedule once a shift, day, or week, self-cleaning filters can be automated to clean at precisely the right time," says Roger Weinberg, Sales Application Specialist for RPA Process Technologies.
"Self-cleaning is controlled by the pressure differential between inlet and outlet headers as contaminants collect on the filter screen," adds Weinberg. "The screens automatically clean themselves when the pressure reaches a predetermined level. This reduces both labor and waste in the filtration process at the source."
Self-cleaning filters not only reduce "waste" but also can turn it into profit
"Dispose of the contaminants, not the filters to reduce waste and lower disposal costs," advises Weinberg. "Since disposable filter media, especially cartridges, absorb process liquid like a sponge, every time you dispose of a cartridge and its contaminants, you're also disposing of your process liquid. Cleanable media eliminate this source of waste and can be used over and over to dramatically lower disposal costs. For instance, cleaning liquid can often be recycled for additional cleaning, and at times the contaminant itself can be recycled into the manufacturing process as a raw material."
Self-cleaning filters dramatically reduce emissions and future liability
With disposable media, the filter is opened every time the media is replaced. This can potentially expose workers and the environment to VOC's (volatile organic compounds) or other toxic emissions. Disposable filters also routinely spill some liquid when removed and placed in disposal drums. Quite often, workers simply hose this process liquid to a drain, which adds to potential exposure and waste treatment cost.
Moreover, with disposable filters such as cartridges, contaminants can travel downstream to ruin a product. This can happen, for example, when the knife-edges used to seal cartridges get nicked and permit solids to bypass the media. Contamination can also occur if cartridges aren't stacked properly in the housing, which is a common problem. In some cases, even the media itself can shed and cause downstream contamination.
With a self-cleaning filter, however, the filter is opened only for inspection. This drastically reduces emissions and their potential risks. "Positive elastomeric-to-metal seals can virtually eliminate off-spec product due to solids bypassing the filter media," adds Weinberg. "Because cleanable media are seldom removed from the housing, seal failure almost never occurs. What's more, reducing waste with cleanable media not only minimizes current worker safety and landfill liability, but also that from legislation that could require costly clean-up years from now."
A Top Self-Cleaning Filter Choice for Fine Chemical-based Manufacturers
Self-cleaning, disc-cleaned filters (DCF) are a popular choice for fine chemical-based manufacturers, particularly for use with highly viscous liquids due to their ability to automate filtration, minimize labor, and maximize production. A unique, mechanically cleaned system for a wide range of liquid filtration applications, DCF filters contain a filter screen of slotted wedge wire, or perforated screen, which liquid passes through from the center outward. When cleaning becomes necessary (triggered by time, pressure differential or the operator), a mechanical cleaning disc travels downward across the filter media to remove contaminants. The downward motion ensures all contaminants are driven to the bottom of the filter for effective purging.
At set intervals, or pre-determined changes in pressure, the DCF cleans the filtering screen then purges the trapped solids, without interrupting production. The DCF filters allow filtration and cleaning to occur simultaneously, which maximizes production and flow consistency while reducing product loss and operator intervention. DCF filters are available in a wide range of configurations and sizes, with media retention rates from 15 microns up to 1/4 inch.
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